Calculating Take-Off Speed Using Newton's Third Law

In summary, the question is about finding Bob's take off speed after throwing a rock with a force of 225N. It is assumed that the rock and Bob form a Newtonian action-reaction pair, meaning Bob experiences a force of 225N in the opposite direction. Using kinematics and conservation of momentum, it is determined that Bob's acceleration is 3.0m/s^2 and his take off speed is 0.2m/s. The question was not provided originally, but the simplest way to solve it is through conservation of momentum.
  • #1
Bostonpancake0
42
0
question is 29./ about bob and throwing his rock, I have found a./ (225N) easily enough it is b./ which i cannot figure out. I am assuming that it is a Newtonian action-reaction pair and that the rock pushes back on bob at 225N as well, which would mean Bob's acceleration would be 3.0ms/s^2. But how do i found his take off speed (I'm asuming kinematics but not sure how with missing variables)??


Answer is 0.2m/s which i can't understand??
 
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  • #2
Could you post the complete question.
 
  • #3
hahhaha didnt even post the question, there you go
 

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  • #4
The simplest way to do this is with conservation of momentum.
 
  • #5
thanks, didnt think of that
 

Related to Calculating Take-Off Speed Using Newton's Third Law

1. What is Newton's third law of motion?

Newton's third law of motion states that for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object exerts a force back on the first object that is equal in magnitude but opposite in direction.

2. How does Newton's third law affect everyday life?

Newton's third law can be seen in many everyday situations, such as when we walk or run. As we push our foot against the ground to move forward, the ground pushes back on our foot with an equal force in the opposite direction, allowing us to move forward. It also explains why we feel a recoil when we shoot a gun or why a rocket moves forward when gas is expelled out of the back.

3. Can Newton's third law be violated?

No, Newton's third law is a fundamental law of physics and cannot be violated. It is a result of the conservation of momentum, which states that the total momentum of a system remains constant unless acted upon by an external force.

4. How is Newton's third law related to the other laws of motion?

Newton's third law is closely related to the other two laws of motion. The first law states that an object at rest will remain at rest and an object in motion will remain in motion unless acted upon by an external force. This external force can be explained by Newton's third law, as the force exerted on the object is equal and opposite to the force it exerts on the external object. The second law also ties in with Newton's third law as it states that the acceleration of an object is directly proportional to the net force acting on it, which includes the force from the object's reaction.

5. How is Newton's third law used in engineering and technology?

Engineers and technologists use Newton's third law to design and build machines and structures that can withstand forces and carry out specific tasks. For example, the design of a rocket engine is based on Newton's third law, where the force of the exhaust gas leaving the rocket propels the rocket in the opposite direction. It is also used in creating safety features in cars, such as airbags, which inflate to protect the passengers from the force of a collision.

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